Organic pigment composition for color filters, method for producing same, and color filter

ABSTRACT

Provided is an organic pigment composition for color filters, which can be used preferably for a color filter that allows to produce a liquid crystal display device which has excellent heat resistance, a brighter display screen, and accordingly higher brightness; a method for producing the same; and a color filter which includes the organic pigment composition for color filters. The color filter has higher heat resistance by using the organic pigment composition for color filters which includes a phthalocyanine pigment and a pigment derivative in which the ratio of a multi-substituted phthalimide alkyl group to the whole amount of the pigment derivative is limited.

TECHNICAL FIELD

The present invention relates to an organic pigment composition forcolor filters which is preferably used for producing a color filter of aliquid crystal display device and includes a phthalocyanine pigment anda phthalocyanine pigment derivative, a method for producing the pigmentcomposition for color filters, and a color filter which includes thepigment composition for color filters.

BACKGROUND ART

A color filter of a liquid crystal display device has a red pixel area,a green pixel area, and a blue pixel area. All of these pixel areas havea structure, in which a thin film made of a synthetic resin having anorganic pigment dispersed therein is provided on a substrate, and as theorganic pigment, organic pigments of each color including red, green,and blue are used.

Among these pixel areas, as a blue organic pigment for forming the bluepixel area, in general, an ε-type copper phthalocyanine pigment (C.I.pigment blue 15:6) is used, and if necessary, in order to mix colors, asmall amount of a dioxazine violet pigment (C.I. pigment violet 23) of aviolet organic pigment or a violet dye is used in combination.

The organic pigments used when producing a color filter are required tohave properties which are totally different from the conventionalorganic pigments used for general purpose. Specifically, the organicpigments are required to cause a display screen of the liquid crystaldisplay device to be brighter (increase brightness) or, in the samemanner, to cause a display screen to be seen much clearly (increasecontrast). Furthermore, since a color filter is exposed to thetemperature of 200° C. or higher because of film attachment oftransparent electrodes or alignment film attachment of polyimide in thestep after producing a color filter, a pigment for color filters whichhas excellent heat resistance and satisfies the above-mentionedproperties has been reviewed.

Meanwhile, a phthalocyanine pigment similar to the present invention isdisclosed, for example, in the following documents.

PTL 1 discloses a method for producing a pigment composition whichincludes an ε-type phthalocyanine pigment and a phthalocyanine pigmentderivative being substituted with a phthalimide methyl group with thenumber of the substituents being 1 to 4; however, a distribution of thesubstituents of the pigment derivative is not mentioned, and heatresistance is not sufficient to satisfy the heat resistance demanded inrecent years.

In the same manner, PTL 2 and PTL 3 suggest a pigment composition forcolor filters which includes a fine ε-type copper phthalocyanine pigmentand a phthalocyanine pigment derivative which has been substituted witha phthalimide methyl group with the number of the substituents being 1to 4, and a method for producing the pigment composition by solvent saltmilling. However, in the same manner as PTL 1, a distribution of thesubstituent of the pigment derivative is not mentioned and theinventions of PTL 2 and PTL 3 are insufficient for obtaining desiredheat resistance.

However, when an organic pigment composition which includes a pigmentderivative in which the ratio of a multi-substituted phthalimide alkylgroup to the whole amount of the pigment derivative is specified as inthe present invention and a phthalocyanine pigment is used for a colorfilter, brightness is less decreased and high heat resistance isobtained, even if the organic pigment composition undergoes a thermalhistory at high temperature in a step of producing a color filter.

CITATION LIST Patent Literature

[PTL 1] JP-A-2013-203868

[PTL 2] JP-A-2008-185703

[PTL 3] JP-A-2008-308605

SUMMARY OF INVENTION Technical Problem

The present invention relates to an organic pigment composition forcolor filters which causes brightness to be less decreased and which hasexcellent heat resistance, even if the organic pigment compositionundergoes a thermal history at high temperature at the time of producinga color filter, a method for producing the same, and a color filterwhich includes the organic pigment composition for color filters usedfor the blue pixel area.

Solution to Problem

As a result of thorough study of the organic pigment composition forcolor filters which can be preferably used for the blue pixel area of acolor filter, the present inventors have found that, in terms of aphthalocyanine pigment and a phthalimide alkyl group pigment derivative,a pigment derivative having the certain ratio of a multi-substitutedphthalimide alkyl group pigment derivative is used; and accordingly, acolor filter having higher heat resistance is provided, therebycompleting the present invention.

That is, the present invention is as follows.

An organic pigment composition for color filters includes aphthalocyanine pigment (A) and a pigment derivative (B) represented byGeneral Formula (1).

(In General Formula (1), M represents a metal which may have asubstituent or 2H, Z represents a phthalimide alkyl group which may havea substituent, n1, n2, n3, and n4 represent the number of thesubstituent Z and each independently is an integer of 0 to 4, providedthat when N=n1+n2+n3+n4, a relation of 1≤N≤8 is satisfied, and a sum ofthe strength ratio of pigment derivatives having an N of 3 to 8 in fielddesorption ionization mass spectrometry is 30% or less of a sum of thestrength ratio of pigment derivatives having an N of 1 to 8.)

The organic pigment composition for color filters, in which, in GeneralFormula (1), a sum of the strength ratio of pigment derivatives havingan N of 4 to 8 in field desorption ionization mass spectrometry may be15% or less of a sum of the strength ratio of pigment derivatives havingan N of 1 to 8.

The organic pigment composition for color filters, in which M in GeneralFormula (1) may represent a monovalent to tetravalent metal which mayhave a substituent.

The organic pigment composition for color filters, in which 0.1 parts to50.0 parts of the pigment derivative (B) may be included per 100 partsof the phthalocyanine pigment (A) by mass.

A method for producing the organic pigment composition for color filtersincludes a step of performing solvent salt milling of a mixture whichincludes crude phthalocyanine or the phthalocyanine pigment (A), thepigment derivative (B) represented by General Formula (1), awater-soluble inorganic salt, and a water-soluble organic solvent.

The method for producing the organic pigment composition for colorfilters, in which the mixture, which includes crude phthalocyanine orthe phthalocyanine pigment (A), the pigment derivative (B) representedby General Formula (1), a water-soluble inorganic salt, and awater-soluble organic solvent, may further include an acryl resin.

A color filter includes the above-mentioned organic pigment compositionfor color filters.

A color filter includes the organic pigment composition for colorfilters obtained by the above-mentioned method for producing an organicpigment composition for color filters.

Advantageous Effects of Invention

The pigment composition for color filters of the present invention isused for a color filter. Thus, a particularly remarkable technicaleffect is exhibited, in which a liquid crystal display device isobtained, whose brightness is less decreased even if the pigmentcomposition undergoes a thermal history at high temperature at the timeof producing a color filter, and which has excellent heat resistance, abrighter display screen, and accordingly higher brightness.

DESCRIPTION OF EMBODIMENTS

Hereinafter, the present invention will be described in detail.

The present invention relates to an organic pigment composition forcolor filters which includes a phthalocyanine pigment (A) and a pigmentderivative (B) represented by General Formula (1) and a color filterwhich contains the pigment composition.

(In General Formula (1), M represents a metal which may have asubstituent or 2H, Z represents a phthalimide alkyl group which may havea substituent, n1, n2, n3, and n4 represent the number of thesubstituent Z and each independently is an integer of 0 to 4, providedthat when N=n1+n2+n3+n4, a relation of 1≤N≤8 is satisfied, and a sum ofthe strength ratio of pigment derivatives having an N of 3 to 8 in fielddesorption ionization mass spectrometry is 30% or less of a sum of thestrength ratio of pigment derivatives having an N of 1 to 8.)

As the phthalocyanine pigment (A) used for the present invention, anypigment among phthalocyanine-based pigments having a phthalocyanineskeleton can be used. The phthalocyanine pigment is a pigment havinghigh solidity and has a color phase from blue to green, and thephthalocyanine pigment is used in a wide range of purposes such as acolor material, an electronic material, an ink jet, and a color filter.As a pigment used for the blue pixel area used for a color filter,normally, a well-known ε-type phthalocyanine pigment is preferably used.It is known that crystal polymorphism exists in the phthalocyaninepigment, such as α-type, β-type, γ-type, ε-type, δ-type, π-type, ρ-type,X-type, and R-type. However, as the pigment for color filters, an ε-typecopper phthalocyanine pigment which has excellent heat resistance and apreferable color tone is preferred. As the ratio of an ε-type is higher,a pigment composition for color filters which has excellent heatresistance and a preferable color tone can be provided, and the ratio ofan ε-type occupying in the crystal polymorphism is preferably 85% ormore. As the ε-type phthalocyanine pigment, one or more ε-typephthalocyanine selected from ε-type copper phthalocyanine, ε-type zincphthalocyanine, ε-type cobalt phthalocyanine, ε-type nickelphthalocyanine, and ε-type iron phthalocyanine can be exemplified, andas the ε-type phthalocyanine pigment to be used, one or two or moretypes thereof may be mixed. As a preferred ε-type phthalocyaninepigment, ε-type copper phthalocyanine can be exemplified from aviewpoint of a color tone.

Furthermore, as a pigment used for a green pixel area of a color filter,halogenated copper phthalocyanine or halogenated zinc phthalocyaninesuch as C.I. pigment green 7, C.I. pigment green 36, C.I. pigment green58, and C.I. pigment green 59 is preferably used. In recent years, inorder to achieve high color reproduction, a study has been activelyconducted from a bluish green pigment to a yellowish green pigment andthese halogenated phthalocyanines having different color phases can beused in the present invention as well. In the halogenatedphthalocyanine, a difference in central metal makes a difference in acolor phase, crystallinity, and heat resistance, and halogenated copperphthalocyanine, halogenated zinc phthalocyanine, and halogenatedaluminum phthalocyanine are preferably used in a present situation.

The pigment derivative (B) used in the present invention is representedby the following general formula.

(In General Formula (1), M represents a metal which may have asubstituent or 2H, Z represents a phthalimide alkyl group which may havea substituent, n1, n2, n3, and n4 represent the number of thesubstituent Z and each independently is an integer of 0 to 4, providedthat when N=n1+n2+n3+n4, a relation of 1≤N≤8 is satisfied, and a sum ofthe strength ratio of pigment derivatives having an N of 3 to 8 in fielddesorption ionization mass spectrometry is 30% or less of a sum of thestrength ratio of pigment derivatives having an N of 1 to 8.)

In General Formula (1), M represents a metal which may have asubstituent or 2H, specifically, a monovalent metal such as Li, Na, andK, or a divalent to tetravalent metal such as Cu, Zn, Fe, Al, Co, Ti,and Pt, or 2H. In consideration of a synthesis method, yield, and costas an industrial product, Cu, Zn, Al, and 2H are preferred as anindustrial product which is generally introduced to a market. Amongthese, when combined with the phthalocyanine pigment, central metalswhich cause brightness to be decreased at least in the presentinvention, even if the pigment composition undergoes a thermal history,are Cu and Zn.

Next, in General Formula (1), the phthalimide alkyl group represented asZ is a pigment derivative in which a phthalimide alkyl group has beenintroduced into a benzene ring in the outline of a phthalocyanineskeleton. The phthalimide alkyl group is a substituent in which aphthalimide structure has been bonded to alkyl having 1 to 8 carbonatoms. The length of the alkyl group makes a difference in the effect ofdispersibility of the pigment for color filters and affects opticalproperties such as contrast and brightness in a color filter. In thepresent invention, in consideration of dispersibility and opticalproperties, a phthalimide alkyl group having 1 to 8 carbon atoms ispreferably used. Furthermore, a phthalimide methyl group of the alkylgroup having 1 carbon atom is particularly preferable.

In addition, since four phthalimide alkyl groups can be introduced intoeach benzene ring in the outline, sixteen substitutions can be performedin maximum. In the prior art by now, by regulating the number ofphthalimide alkyl group, a study for improving dispersibility, opticalproperties, and heat resistance of the pigment for color filters hasbeen conducted. As a result of thorough study, the present inventorshave found that, in a case where the ratio of the pigment derivative,which has the large number of substitutions of the phthalimide alkylgroup, to the whole amount of the pigment derivative is greater, heatresistance becomes extremely deteriorated, and as a result, brightnessafter a thermal history is considerably decreased.

The thermal history in a color filter is performed by baking the pigmentcomposition at the temperature of 200° or higher in fixation of thecolor filter itself and film formation of a polyimide alignment film,and temperature, time, and the number of baking may be further increaseddepending on the configuration of a display.

The number of phthalimide alkyl group substituted by phthalocyanine ismeasured by field desorption ionization mass spectrometry. Inparticular, when the substituent Z is a phthalimide methyl group, thenumber of substituents of the phthalimide methyl group at the molecularion peak 159 (m/z) is set to an N of 1, the number of substituents iscalculated from the strength ratio based on the ion peak, which is amultiple of the above molecular ion peak. As a result of calculation, ina case where a pigment derivative having a substituent as an N of 3 to 8to the whole substituent numbers (N=1 to 8) 100% is 30% or less, it isclarified that the decreasing ratio of brightness after heat resistancehistory is low. In addition, it is determined that in a case where thepigment derivative is 25% or less, a decrease in brightness is evenless, and in a case where the pigment derivative is 20% or less, adecrease in brightness is further less.

As the content of a pigment derivative of the phthalimide alkyl grouphaving 3 to 8 substituents in the whole pigment derivatives is low, adecrease in brightness after thermal history is low. It is consideredthat the reason for the above is that a multi-substituted pigmentderivative is likely to be decomposed by heat. Since the number ofsubstitution of the multi-substituted pigment derivative is large, amolecular structure is unstable, which causes deterioration in heatresistance. Also, compatibility of the multi-substituted pigmentderivative with a resin is increased. Furthermore, since themulti-substituted pigment derivative has a bulky molecular structure,intermolecular interaction such as π-π stacking between the pigmentderivative and the phthalocyanine pigment is weak. Therefore, when thepigment composition undergoes a thermal history, the pigment derivativewhich has been treated to be a phthalocyanine pigment is effused to aresin component, a particle diameter of the pigment is enlarged, lightscattering occurs, and brightness is decreased. Accordingly, it isconsidered that the organic pigment composition of the present inventionin which the content of the multi-substituted pigment derivative islimited has high heat resistance.

The content of the pigment derivative (B) represented by General Formula(1) of the present invention in the organic pigment composition forcolor filters is preferably 0.1 to 50% by mass with respect to thephthalocyanine pigment (A), and more preferably 2 to 15% by mass from aviewpoint of change in a color phase and color purity affected by thecontent of the pigment derivative. If the content of the pigmentderivative is less than 2% by mass, heat resistance of the pigmentderivative caused by a crystal growth inhibiting effect cannot beexpected, and if the content of the pigment derivative exceeds 15% bymass, influence on a blue color phase becomes greater, which is notpreferable.

The organic pigment composition for color filters of the presentinvention can be obtained by performing solvent salt milling of amixture, which includes crude phthalocyanine or the phthalocyaninepigment (A), the pigment derivative (B) represented by General Formula(1) of the present invention, a water-soluble inorganic salt, andwater-soluble organic solvent. As an apparatus used for solvent saltmilling, a kneader, a mix muller, Trimix (trade name) manufactured byINOUE MFG., INC., which is a planetary mixer disclosed inJP-A-2007-100008, or MIRACLE KCK manufactured by ASADA IRON WORKS CO.,LTD., which is a continuous monoaxial kneader disclosed inJP-A-2006-306996, can be used.

The solvent salt milling means kneading and grinding of a pigment, aninorganic salt, and an organic solvent. Specifically, a pigment, aninorganic salt, and an organic solvent which does not dissolve thereofare put into a kneader, and kneading and grinding is performed in thekneader.

An acryl resin is further contained in the mixture which includes crudephthalocyanine or the phthalocyanine pigment (A), the pigment derivative(B) represented by General Formula (1) of the present invention, thewater-soluble inorganic salt, and the water-soluble organic solvent.Thus, much preferred organic pigment composition for color filters canbe obtained by solvent salt milling.

The water-soluble inorganic salt can be preferably used as the inorganicsalt, and for example, an inorganic salt such as sodium chloride,potassium chloride, and sodium sulfate is preferably used. In addition,inorganic salt having an average particle diameter of 0.5 to 50 μm ismore preferably used. These inorganic salts are easily obtained byfinely pulverizing common inorganic salts.

The use amount of the inorganic salt is preferably set to 4 to 20 partsby weight and more preferably 6 to 15 parts by weight with respect to 1part by weight of phthalocyanine.

As the organic solvent, a water-soluble organic solvent as the organicsolvent which is able to inhibit crystal growth can be preferably used.For example, diethylene glycol, glycerine, ethylene glycol, propyleneglycol, liquid polyethylene glycol, liquid polypropylene glycol,2-(methoxymethoxy) ethanol, 2-butoxyethanol, 2-(isopentyloxy)ethanol,2-(hexyloxy)ethanol, diethylene glycol monomethyl ether, diethyleneglycol monoethyl ether, diethylene glycol monobutyl ether, triethyleneglycol, triethylene glycol monomethyl ether, 1-methoxy-2-propanol,1-ethoxy-2-propanol, dipropylene glycol, dipropylene glycol monomethylether, dipropylene glycol monomethyl ether, or dipropylene glycol can beused, and ethylene glycol or diethylene glycol is preferable.

The use amount of the water-soluble organic solvent is not particularlylimited, and preferably 0.01 to 5 parts by weight with respect to 1 partby weight of the pigment.

As the acryl resin, a polymer of at least one or more (meth)acrylic acidester monomers is used. In addition, a polymer may be used, in which oneor more (meth)acrylic acid esters and other monomers which arecopolymerizable with (meth)acrylic acid esters are used in combination.

As the (meth)acrylic acid alkyl ester monomer, for example,(meth)acrylic acid alkyl ester having an alkyl group such asmethyl(meth)acrylate, ethyl(meth)acrylate, n-propyl(meth)acrylate,isopropyl(meth)acrylate, n-butyl(meth)acrylate, isobutyl(meth)acrylate,tert-butyl(meth)acrylate, 2-ethyl hexyl(meth)acrylate,n-octyl(meth)acrylate, dodecyl(meth)acrylate[lauryl(meth)acrylate], andoctadecyl(meth)acrylate[stearyl(meth)acrylate], (meth)acrylic acid esterhaving a alicyclic group such as cyclohexyl(meth)acrylate,isobornyl(meth)acrylate, adamantyl(meth)acrylate, anddicyclopentanyl(meth)acrylate, which is (meth)acrylic acid alkyl ester;(meth)acrylic acid ester having an ether group such asmethoxytriethylene glycol(meth)acrylate, methoxypolyethyleneglycol#400(meth)acrylate, methoxydipropylene glycol(meth)acrylate,methoxytripropylene glycol(meth)acrylate, methoxypolypropyleneglycol(meth)acrylate, ethyl carbitol(meth)acrylate, 2-ethyl hexylcarbitol(meth)acrylate, tetrahydrofurfuryl(meth)acrylate,phenoxyethyl(meth)acrylate, phenoxydiethylene glycol(meth)acrylate,p-nonyl phenoxyethyl(meth)acrylate, and p-nonyl phenoxypolyethyleneglycol(meth)acrylate; and (meth)acrylic acid ester having an aromaticring such as benzyl(meth)acrylate, can be used.

As other monomers which are copolymerizable with the (meth)acrylic acidester monomer, for example, vinyl esters such as vinyl acetate, vinylpropionate, and tertiary vinyl carboxylate; heterocyclic vinyl compoundssuch as vinyl pyrrolidone; halogenated olefins such as vinyl chloride,vinylidene chloride, and vinylidene fluoride; cyano group-containingmonomers such as acrylonitrile and methacrylonitrile; vinyl ethers suchas ethyl vinyl ether and isobutyl vinyl ether; vinyl ketones such asmethyl vinyl ketone; α-olefins such as ethylene and propylene; dienessuch as butadiene and isoprene; and styrene-based monomers such asstyrene, vinyl toluene, α-methyl styrene, dimethyl styrene, tert-butylstyrene, and chlorostyrene, can be used.

The use amount of the acryl resin is not particularly limited andpreferably 0.01 to 1 parts by weight with respect to 1 part by weight ofthe pigment. In addition, if the use amount of the acryl resin is large,transparent components in the organic pigment composition for colorfilters are increased and coloring power is decreased. Thus, the useamount is more preferably 0.02 to 0.2 parts by weight.

Kneading is preferably performed at the temperature of 50° C. to 120° C.Even if kneading is performed at the temperature of less than 50° C., apercentage of ε conversion (ε-type crystallization ratio included incopper phthalocyanine) of the ε-type copper phthalocyanine is low, whichis not preferable. Also, even if kneading is performed at thetemperature exceeding 120° C., the size of pigment particles cannot bedecreased sufficiently and contrast is decreased, which is notpreferable as the organic pigment composition for color filters.

The organic pigment composition for color filters of the presentinvention may include free copper. The free copper to be included may befree copper remaining when copper phthalocyanine is synthesized or freecopper generated by decomposition of the synthesized copperphthalocyanine. The free copper can be washed by acids. As the acids tobe used, for example, hydrochloric acid and sulfuric acid can beexemplified, and concentration of the hydrochloric acid or sulfuric acidis preferably 0.5% to 4%. The temperature at the time of washing ispreferably 50 to 90° C. Water may be used for washing. The preferablecontent of the free copper is 900 mass ppm or less in the pigmentcomposition and in a case where the content is more than the above, heatresistance of the color filter to be obtained is decreased, which is notpreferable.

In the organic pigment composition for color filters of the presentinvention, dispersibility to a liquid medium and dispersion stabilityare high, viscosity of a pigment dispersion described below is low, andNewtonian fluidity is high and stable from that the pigment compositionis dispersed as fine particles. In a case where the blue pixel area of acolor filter is produced, a uniform coating film is formed andaccordingly, a color filter having high brightness, high contrast, andhigh light transmittance can be obtained. Here, the organic pigmentcomposition for color filters of the present invention is characterizedto include the phthalocyanine pigment (A) and the pigment derivative (B)represented by General Formula (1), and if necessary, even if thepigment composition includes a pigment for mixing colors such as adioxazine-based pigment (C.I. pigment violet 23, C.I. pigment violet 37,C.I. pigment blue 80, or the like); an organic pigment derivative suchas a sulfuric acid derivative of metal-free or metal phthalocyanine, aN-(dialkyl amino)methyl derivative of metal-free or metalphthalocyanine, a N-(dialkyl aminoalkyl)sulfonic acid amide derivativeof metal-free or metal phthalocyanine, a sulfuric acid derivative ofdioxazine violet, a sulfuric acid derivative of indanthrene blue, andphthalocyanine sulfuric acid; a dispersant such as DISPERBYK 130,DISPERBYK 161, DISPERBYK 162, DISPERBYK 163, DISPERBYK 170, DISPERBYK171, DISPERBYK 174, DISPERBYK 180, DISPERBYK 182, DISPERBYK 183,DISPERBYK 184, DISPERBYK 185, DISPERBYK 2000, DISPERBYK 2001, DISPERBYK2020, DISPERBYK 2050, DISPERBYK 2070, DISPERBYK 2096, and DISPERBYK 2150of BYK Additives & Instruments, Efka 46, Efka 47, Efka 452, Efka LP4008,Efka 4009, Efka LP4010, Efka LP4050, LP4055, Efka 400, Efka 401, Efka402, Efka 403, Efka 450, Efka 451, Efka 453, Efka 4540, Efka 4550, EfkaLP4560, Efka 120, Efka 150, Efka 1501, Efka 1502, and Efka 1503 of EfkaChemicals, Solsperse 3000, Solsperse 9000, Solsperse 13240, Solsperse13650, Solsperse 13940, Solsperse 17000, 18000, Solsperse 20000,Solsperse 21000, Solsperse 20000, Solsperse 24000, Solsperse 26000,Solsperse 27000, Solsperse 28000, Solsperse 32000, Solsperse 36000,Solsperse 37000, Solsperse 38000, Solsperse 41000, Solsperse 42000,Solsperse 43000, Solsperse 46000, Solsperse 54000, and Solsperse 71000of Lubrizol Corporation, AJISPER PB711, AJISPER PB821, AJISPER PB822,AJISPER PB814, AJISPER PN411, and AJISPER PA111 of AJINOMOTO., INC.; anda resin including a natural rosin such as an acryl-based resin, anurethane-based resin, an alkyd-based resin, a wood rosin, a gum rosin,and a tall oil rosin, a modified rosin such as a polymerized rosin, adisproportionated rosin, a hydrogenated rosin, an oxidized rosin, and amaleated rosin, and a rosin derivative such as rosin amine, lime rosin,rosin alkylene oxide adducts, rosin alkyl adducts, and rosin-modifiedphenol, the pigment composition can be preferably used for the bluepixel area of a color filter. Addition of these organic pigmentderivative, dispersant, and resin contributes to a decrease inflocculation, enhancement of dispersion stability of the pigment, andenhancement of viscosity of the dispersing element.

The organic pigment composition for color filters of the presentinvention can be preferably used, mainly for the blue pixel area of acolor filter according to the conventionally well-known method. Inaddition, the organic pigment composition can be used for other redpixel area, green pixel area, and black matrix configuring a colorfilter, or for coloring a column spacer configuring a display. The useof the organic pigment composition for color filters of the presentinvention is not limited to the blue pixel area of a color filter.

Photolithography method is a representative method among the methods fordispersing the composition of the present invention. This method isperformed such that a photocurable composition described below is coatedon the surface on the side on which a black matrix of a transparentsubstrate for color filters is provided, heated, and dried (prebaked),and then the composition is irradiated with ultraviolet rays via aphotomask to expose a pattern, a photocurable compound in the areacorresponding to the pixel area is cured, and then an unexposed area isdeveloped by a developing solution, and a non-pixel area is removed tofix the pixel area to the transparent substrate. According to thismethod, a pixel area including a cured colored film of the photocurablecomposition is formed on the transparent substrate. A photocurablecomposition described below is prepared for each red, green, and bluecolor and the above-mentioned operation is performed repetitively,thereby producing a color filter having pixel area colored by red,green, and blue on the predetermined positions.

As a pigment for forming a red pixel area, for example, C.I. pigment red177, C.I. pigment red 209, C.I. pigment red 254, and the like areexemplified, and as a pigment for forming a green pixel area, forexample, C.I. pigment green 7, C.I. pigment green 10, C.I. pigment green36, C.I. pigment green 47, C.I. pigment green 58, C.I. pigment green 59,and the like are exemplified. A yellow pigment can be used incombination in order to form these red pixel area and green pixel area.Thereafter, if necessary, in order to thermally cure the unreactedphotocurable compound, the whole color filter can be heated(post-baked).

A spin coating method, a roll coating method, an ink jet method, and thelike are exemplified as a method for coating the photocurablecomposition described below on the transparent substrate such as aglass.

A drying condition of the coating film of the photocurable compositioncoated on the transparent substrate differs depending on the type ofeach component, a blending ratio, or the like, and normally, thetemperature is 50° C. to 150° C. and the time is about 1 to 15 minutes.In addition, as the light used for photocuring of the photocurablecomposition, ultraviolet rays in the wavelength range of 200 to 500 nmor visible rays are preferably used. A variety of light sources emittingrays of this wavelength range can be used.

A puddle method, a dipping method, a spray method, or the like isexemplified as a developing method. The photocurable composition isexposed and developed and then the transparent substrate on which pixelareas with demanded colors are formed is washed by water and dried. Thecolor filter obtained by this way is heated (post-baked) by a heatingapparatus such as a hotplate and an oven at the temperature of 90° C. to280° C. for a predetermined period of time, and accordingly volatilecomponents in the colored coating film are removed and, at the sametime, the unreacted photocurable compound remaining in the cured coloredfilm of the photocurable composition is thermally cured, therebycompleting a color filter.

The photocurable composition for forming a pixel area of a color filteressentially includes organic pigment composition for color filters ofthe present invention, a dispersant, a photocurable compound, and anorganic solvent, and can be prepared by mixing these components using athermoplastic resin according to the necessity. In a case where thecolored resin film for forming a pixel area requires toughness demandedin order to endure baking, which is conducted for real production of acolor filter, when preparing the photocurable composition, not only thephotocurable compound but also this thermoplastic resin is inevitablyused in combination. In a case where the thermoplastic resin is used incombination, an organic solvent which dissolves the thermoplastic resinis preferably used.

As a method for producing the photocurable composition, the method isgeneral, in which the pigment composition of the present invention, anorganic solvent, and a dispersant are essentially used, these componentsare mixed, stirred and dispersed so as to be uniform, and, firstly,after a pigment dispersion for forming a pixel area of a color filter isprepared, the photocurable compound and if necessary, the thermoplasticresin or a photopolymerization initiator are added to obtain thephotocurable composition.

Here, the above-mentioned dispersant and the organic solvent can beused.

Examples of the thermoplastic resin used for preparing the photocurablecomposition include a urethane-based resin, an acryl-based resin, apolyamide-based resin, a polyimide-based resin, a styrene maleicacid-based resin, and a styrene maleic anhydride resin.

Examples of the photocurable compound include a bifunctional monomersuch as 1,6-hexane diol diacrylate, ethylene glycol diacrylate,neopentyl glycol diacrylate, triethylene glycol diacrylate,bis(acryloxyethoxy)bisphenol A, and 3-methyl pentane diol diacrylate; apolyfunctional monomer having a relatively small molecular weight suchas trimethylolpropanetriacrylate, pentaerythritol triacrylate,tris(2-hydroxyethyl)isocyanate, dipentaerythritol hexaacrylate, anddipentaerythritol pentaacrylate; a polyfunctional monomer having arelatively large molecular weight such as polyester acrylate,polyurethane acrylate, and polyether acrylate.

Examples of the photopolymerization initiator include acetophenone,benzophenone, benzyl dimethyl ketal, benzoyl peroxide,2-chlorothioxanthone, 1,3-bis(4′-azido benzal)-2-propane,1,3-bis(4′-azido benzal)-2-propane-2′-sulfonic acid, and 4,4′-diazidostilbene-2,2′-disulfonic acid. Examples of the commercially availablephotopolymerization initiator include “IRGACURE (trade name)-184”,“IRGACURE (trade name)-369”, and “DAROCUR (trade name)-1173”manufactured by Ciba Specialty Chemicals Corporation, “Lucirin-TPO”manufactured by BASF Japan Ltd., “Kayacure (trade name) DETX” and“Kayacure (trade name) OA” manufactured by Nippon Kayaku Co., Ltd.,“Baikyua 10” and “Baikyua 55” manufactured by Sutoufa Chemical Co.,“Trigonal PI” manufactured by Akzo Co., Ltd., “Sandorei 1000”manufactured by Sandozu Co., Ltd., “Deep” manufactured by Apujon Co.,Ltd., and “Biimidazole” manufactured by Kurogane Kasei Co., Ltd.

A well-known and commonly used photosensitizer can be used incombination with the above-mentioned photopolymerization initiator.Examples of the photosensitizer include amines, ureas, a compound havinga sulfur atom, a compound having a phosphorous atom, a compound having achlorine atom, nitriles, or a compound having a nitrogen atom. These maybe used alone or two or more thereof may be used in combination. Ablending ratio of the photopolymerization initiator is not particularlylimited, and preferably, by mass, in the range of 0.1% to 30% withrespect to a compound having a photopolymerizable or photocurablefunctional group. If the blending ratio is less than 0.1%,photosensitivity at the time of photocuring tends to be decreased, andif the blending ratio exceeds 30%, when a coating film of apigment-dispersed resist is dried, a crystal of the photopolymerizationinitiator is precipitated, which causes deterioration in physicalproperties of the coating film.

By using each material as described above, the pigment dispersion can beobtained by stirring and dispersing, by mass, 300 to 1000 parts of anorganic solvent and 1 to 100 parts of a dispersant per 100 parts of theorganic pigment composition for color filters of the present inventionso as to be uniform. Next, total 0.5 to 20 parts of a thermoplasticresin and a photocurable compound per 1 part of the pigment compositionof the present invention, 0.05 to 3 parts of a photopolymerizationinitiator per 1 part of the photocurable compound, and if necessary, anorganic solvent are added to this pigment dispersion, and the resultantare stirred and dispersed so as to be uniform, thereby obtaining aphotocurable composition for forming the blue pixel area of a colorfilter.

A well-known and commonly used organic solvent or an alkali aqueoussolution can be used as a developing solution. In particular, athermoplastic resin or a photocurable compound is included in thephotocurable composition, and in a case where at least one of the abovehas an acid value and exhibits solubility in alkali, washing by analkali aqueous solution is effective for forming a pixel area of a colorfilter.

Among the methods for dispersing a pigment, a method for producing apixel area of a color filter according to a photolithography method isdescribed in detail, and the pixel area of a color filter prepared byusing the organic pigment composition for color filters of the presentinvention may be formed according to other methods such as anelectrodeposition method, a transfer method, a micelle electrolyticmethod, a photovoltaic electrodeposition (PVED) method, an ink jetmethod, a reverse printing method, and a thermosetting method to producea color filter.

A color filter can be obtained as follows: a photocurable composition ofeach color obtained by using a blue pigment, a red pigment, and a greenpigment is used, a liquid crystal material is enclosed between a pair oftransparent electrodes parallel to each other, the transparentelectrodes are divided into discontinuous fine sections, and a coloredpixel area of a color filter selected from any one color of red, green,and blue is alternatively provided in a pattern shape, to each of thefine sections divided in a grid shape by a black matrix on thetransparent electrodes; or a colored pixel area of a color filter isformed on the substrate and then the transparent electrodes areprovided.

An organic pigment dispersing element obtained from the organic pigmentcomposition for color filters of the present invention is a pigmentdispersing element having excellent clarity and brightness, and can beapplied to, in addition to the use of a color filter, coloring a coatingmaterial, plastic (resin molded article), a printing ink, rubber,leather, textile printing, an electrostatic charge image developingtoner, an ink jet recording ink, and a thermal transfer ink.

EXAMPLES

Hereinafter, the present invention is described in detail usingExamples, and originally, the present invention is not limited to therange of Examples. In addition, all of “parts” and “%” are based onmass, unless otherwise mentioned.

In addition, the items described below in Synthesis Examples, Examples,and Comparative Examples are measured as follows.

(Measurement of Substituent Distribution of Pigment Derivative)

A substituent distribution of the pigment derivative was measuredaccording to field desorption ionization mass spectrometry by usingJMS-T100GC manufactured by JEOL Ltd. 5 mg of a sample was added to 1.0mL of tetrahydrofuran which does not contain dibutyl hydroxytoluene andsuspended by ultrasonic waves to be used for measurement.

[Measurement Condition]

Emitter current: 0 mA to 40 mA [25.6 mA/min]

Counter electrode: −10000 V

Measurement mass range: m/z=50 to 200

Measurement time: 2 minutes

In the mass spectrometry obtained by field desorption ionization massspectrometry, a sum of the molecular peak ionic strength of the pigmentderivative having an N of 1 to 8 of the substituent Z is set to 100%,and the molecular peak ionic strength ratio of the pigment derivativehaving an N of 3 to 8 with respect to the molecular peak ionic strengthof the pigment derivative having an N of 1 to 8 was calculated.

(Evaluation of Brightness Difference ΔY Before and after Baking)

By using a color filter before baking at the temperature of 230° C. anda color filter after baking at the temperature of 230° C., brightness Yof the chromaticity y=0.110 in the light source C was measured byMCPD-3000 (manufactured by OTSUKA ELECTRONICS Co., Ltd.). The brightnessdifference ΔY before and after baking was obtained by subtracting thebrightness Y before baking from the brightness Y after baking. As thebrightness difference ΔY is closer to 0, brightness is less decreasedand heat resistance is excellent.

Synthesis Example 1 [Synthesis of Pigment Derivative (B-1)]

988 parts of 98% sulfuric acid (manufactured by NIPPON PHOSPHORIC ACIDCO., JP) and 366 parts of 25% fuming sulfuric acid (manufactured by WakoPure Chemical Industries, Ltd.) were put into a flask equipped with astirrer, a thermometer, and a cooling tube, while being cooled in ice.After the temperature of the flask was increased to 30° C., 55 parts ofphthalimide (manufactured by Wako Pure Chemical Industries, Ltd.) wasadded thereto and the temperature thereof was increased to 40° C.Thereafter, 20 parts of 92% paraformaldehyde (manufactured by MITSUBISHIGAS CHEMICAL COMPANY, INC.) was added thereto and stirred for 30minutes. Next, 80 parts of a β-type copper phthalocyanine pigment(manufactured by DIC Corporation) was added thereto and stirred for 30minutes. Subsequently, the temperature thereof was increased to 80° C.and stirred for 4 hours, and then the temperature was cooled down toroom temperature. After cooling off, 7500 parts of water having roomtemperature was added thereto and stirred for 1 hour, and then areaction solution was filtered. A filtrate was washed with water untilthe specific conductivity of the filtrate becomes not more than (thespecific conductivity of the original water+50 μS/cm), thereby obtaininga wet cake of a pigment derivative. The obtained wet cake was dried atthe temperature of 90° C. by blowing air for 24 hours to obtain apigment derivative (B-1).

The pigment derivative (B-1) was analyzed according to field desorptionionization mass spectrometry and it was confirmed that the pigmentderivative (B-1) is a compound in which M is a copper atom, asubstituent Z is a phthalimide methyl group, and N=1 to 8 in GeneralFormula (1). The result of field desorption ionization mass spectrometryis shown in Table 1.

TABLE 1 Result of Field Desorption Number of Ionization MassSpectrometry Substituent Z Molecular Ion Peak N m/z Strength Ratio 1 73453.2% 2 893 20.3% 3 1052 13.5% Total of N = 3 4 1211 8.7% to 8: 26.5% 51370 3.0% 6 1529 1.1% 7 1689 0.1% 8 1848 0.1%

Synthesis Example 2 [Synthesis of Pigment Derivative (B-2)]

485 parts of 98% sulfuric acid (manufactured by NIPPON PHOSPHORIC ACIDCO., JP) and 170 parts of 25% fuming sulfuric acid (manufactured by WakoPure Chemical Industries, Ltd.) were put into a flask equipped with astirrer, a thermometer, and a cooling tube, while being cooled in ice.After the temperature of the flask was increased to 30° C., 38 parts ofphthalimide (manufactured by Wako Pure Chemical Industries, Ltd.) wasadded thereto and the temperature thereof was increased to 40° C.Thereafter, 17 parts of 92% paraformaldehyde (manufactured by MITSUBISHIGAS CHEMICAL COMPANY, INC.) was added thereto and stirred for 30minutes. Next, 110 parts of a β-type copper phthalocyanine pigment(manufactured by DIC Corporation) was added thereto and stirred for 30minutes. Subsequently, the temperature thereof was increased to 80° C.and stirred for 4 hours, and then the temperature was cooled down toroom temperature. After cooling off, 7500 parts of water having roomtemperature was added thereto and stirred for 1 hour, and then areaction solution was filtered. A filtrate was washed with water untilthe specific conductivity of the filtrate becomes not more than (thespecific conductivity of the original water+50 μS/cm), thereby obtaininga wet cake of a pigment derivative. The obtained wet cake was dried atthe temperature of 90° C. by blowing air for 24 hours to obtain apigment derivative (B-2).

The pigment derivative (B-2) was analyzed according to field desorptionionization mass spectrometry and it was confirmed that the pigmentderivative (B-2) is a compound in which M is a copper atom, asubstituent Z is a phthalimide methyl group, and N=1 to 8 in GeneralFormula (1). The result of field desorption ionization mass spectrometryis shown in Table 2.

TABLE 2 Result of Field Desorption Number of Ionization MassSpectrometry Substituent Z Molecular Ion Peak N m/z Strength Ratio 1 73457.4% 2 893 21.4% 3 1052 12.9% Total of N = 3 4 1211 6.2% to 8: 21.2% 51370 1.4% 6 1529 0.5% 7 1689 0.1% 8 1848 0.1%

Synthesis Example 3 [Synthesis of Pigment Derivative (B-3)]

520 parts of 98% sulfuric acid (manufactured by NIPPON PHOSPHORIC ACIDCO., JP) and 170 parts of 25% fuming sulfuric acid (manufactured by WakoPure Chemical Industries, Ltd.) were put into a flask equipped with astirrer, a thermometer, and a cooling tube, while being cooled in ice.After the temperature of the flask was increased to 30° C., 26 parts ofphthalimide (manufactured by Wako Pure Chemical Industries, Ltd.) wasadded thereto and the temperature thereof was increased to 40° C.Thereafter, 10 parts of 92% paraformaldehyde (manufactured by MITSUBISHIGAS CHEMICAL COMPANY, INC.) was added thereto and stirred for 30minutes. Next, 118 parts of a β-type copper phthalocyanine pigment(manufactured by DIC Corporation) was added thereto and stirred for 30minutes. Subsequently, the temperature thereof was increased to 80° C.and stirred for 4 hours, and then the temperature was cooled down toroom temperature. After cooling off, 7500 parts of water having roomtemperature was added thereto and stirred for 1 hour, and then areaction solution was filtered. A filtrate was washed with water untilthe specific conductivity of the filtrate becomes not more than (thespecific conductivity of the original water+50 μS/cm), thereby obtaininga wet cake of a pigment derivative. The obtained wet cake was dried atthe temperature of 90° C. by blowing air for 24 hours to obtain apigment derivative (B-3).

The pigment derivative (B-3) was analyzed according to field desorptionionization mass spectrometry and it was confirmed that the pigmentderivative (B-3) is a compound in which M is a copper atom, asubstituent Z is a phthalimide methyl group, and N=1 to 8 in GeneralFormula (1). The result of field desorption ionization mass spectrometryis shown in Table 3.

TABLE 3 Result of Field Desorption Number of Ionization MassSpectrometry Substituent Z Molecular Ion Peak N m/z Strength Ratio 1 73459.7% 2 893 22.7% 3 1052 12.2% Total of N = 3 4 1211 4.5% to 8: 17.6% 51370 0.7% 6 1529 0.2% 7 1689 0.1% 8 1848 0.1%

Synthesis Example 4 [Synthesis of Pigment Derivative (B-4)]

988 parts of 98% sulfuric acid (manufactured by NIPPON PHOSPHORIC ACIDCO., JP) and 366 parts of 25% fuming sulfuric acid (manufactured by WakoPure Chemical Industries, Ltd.) were put into a flask equipped with astirrer, a thermometer, and a cooling tube, while being cooled in ice.After the temperature of the flask was increased to 30° C., 55 parts ofphthalimide (manufactured by Wako Pure Chemical Industries, Ltd.) wasadded thereto and the temperature thereof was increased to 40° C.Thereafter, 20 parts of 92% paraformaldehyde (manufactured by MITSUBISHIGAS CHEMICAL COMPANY, INC.) was added thereto and stirred for 30minutes. Next, 81 parts of a zinc phthalocyanine pigment (manufacturedby DIC Corporation) was added thereto and stirred for 30 minutes.Subsequently, the temperature thereof was increased to 70° C. andstirred for 4 hours, and then the temperature was cooled down to roomtemperature. After cooling off, 7500 parts of water having roomtemperature was added thereto and stirred for 1 hour, and then areaction solution was filtered. A filtrate was washed with water untilthe specific conductivity of the filtrate becomes not more than (thespecific conductivity of the original water+50 μS/cm), thereby obtaininga wet cake of a pigment derivative. The obtained wet cake was dried atthe temperature of 90° C. by blowing air for 24 hours to obtain apigment derivative (B-4).

The pigment derivative (B-4) was analyzed according to field desorptionionization mass spectrometry and it was confirmed that the pigmentderivative (B-4) is a compound in which M is a zinc atom, a substituentZ is a phthalimide methyl group, and N=1 to 8 in General Formula (1).The result of field desorption ionization mass spectrometry is shown inTable 4.

TABLE 4 Result of Field Desorption Number of Ionization MassSpectrometry Substituent Z Molecular Ion Peak N m/z Strength Ratio 1 73553.5% 2 894 21.3% 3 1053 12.8% Total of N = 3 4 1212 8.5% to 8: 25.2% 51371 3.2% 6 1530 0.5% 7 1690 0.1% 8 1849 0.1%

Synthesis Example 5 [Synthesis of Pigment Derivative (B-5)]

520 parts of 98% sulfuric acid (manufactured by NIPPON PHOSPHORIC ACIDCO., JP) and 170 parts of 25% fuming sulfuric acid (manufactured by WakoPure Chemical Industries, Ltd.) were put into a flask equipped with astirrer, a thermometer, and a cooling tube, while being cooled in ice.After the temperature of the flask was increased to 30° C., 25 parts ofphthalimide (manufactured by Wako Pure Chemical Industries, Ltd.) wasadded thereto and the temperature thereof was increased to 40° C.Thereafter, 10 parts of 92% paraformaldehyde (manufactured by MITSUBISHIGAS CHEMICAL COMPANY, INC.) was added thereto and stirred for 30minutes. Next, 125 parts of a zinc phthalocyanine pigment (manufacturedby DIC Corporation) was added thereto and stirred for 30 minutes.Subsequently, the temperature thereof was increased to 70° C. andstirred for 4 hours, and then the temperature was cooled down to roomtemperature. After cooling off, 7500 parts of water having roomtemperature was added thereto and stirred for 1 hour, and then areaction solution was filtered. A filtrate was washed with water untilthe specific conductivity of the filtrate becomes not more than (thespecific conductivity of the original water+50 μS/cm), thereby obtaininga wet cake of a pigment derivative. The obtained wet cake was dried atthe temperature of 90° C. by blowing air for 24 hours to obtain apigment derivative (B-5).

The pigment derivative (B-5) was analyzed according to field desorptionionization mass spectrometry and it was confirmed that the pigmentderivative (B-5) is a compound in which M is a zinc atom, a substituentZ is a phthalimide methyl group, and N=1 to 8 in General Formula (1).The result of field desorption ionization mass spectrometry is shown inTable 5.

TABLE 5 Result of Field Desorption Number of Ionization MassSpectrometry Substituent Z Molecular Ion Peak N m/z Strength Ratio 1 73563.1% 2 894 20.5% 3 1053 10.7% Total of N = 3 4 1212 4.2% to 8: 16.4% 51371 1.1% 6 1530 0.3% 7 1690 0.1% 8 1849 0.0%

Synthesis Example 6 [Synthesis of Comparative Pigment Derivative (B′-1)]

913 parts of 98% sulfuric acid (manufactured by NIPPON PHOSPHORIC ACIDCO., JP) and 366 parts of 25% fuming sulfuric acid (manufactured by WakoPure Chemical Industries, Ltd.) were put into a flask equipped with astirrer, a thermometer, and a cooling tube, while being cooled in ice.After the temperature of the flask was increased to 30° C., 70 parts ofphthalimide (manufactured by Wako Pure Chemical Industries, Ltd.) wasadded thereto and the temperature thereof was increased to 40° C.Thereafter, 28 parts of 92% paraformaldehyde (manufactured by MITSUBISHIGAS CHEMICAL COMPANY, INC.) was added thereto and stirred for 30minutes. Next, 80 parts of a β-type copper phthalocyanine pigment(manufactured by DIC Corporation) was added thereto and stirred for 30minutes. Subsequently, the temperature thereof was increased to 80° C.and stirred for 4 hours, and then the temperature was cooled down toroom temperature. After cooling off, 7500 parts of water having roomtemperature was added thereto and stirred for 1 hour, and then areaction solution was filtered. A filtrate was washed with water untilthe specific conductivity of the filtrate becomes not more than (thespecific conductivity of the original water+50 μS/cm), thereby obtaininga wet cake of a pigment derivative. The obtained wet cake was dried atthe temperature of 90° C. by blowing air for 24 hours to obtain acomparative pigment derivative (B′-1).

The comparative pigment derivative (B′-1) was analyzed according tofield desorption ionization mass spectrometry and it was confirmed thatthe comparative pigment derivative (B′-1) is a compound in which M is acopper atom, a substituent Z is a phthalimide methyl group, and N=1 to 8in General Formula (1). The result of field desorption ionization massspectrometry is shown in Table 6.

TABLE 6 Result of Field Desorption Number of Ionization MassSpectrometry Substituent Z Molecular Ion Peak N m/z Strength Ratio 1 73449.3% 2 893 19.7% 3 1052 13.2% Total of N = 3 4 1211 10.7% to 8: 31.0% 51370 5.2% 6 1529 1.8% 7 1689 0.0% 8 1848 0.1%

Synthesis Example 7 [Synthesis of Comparative Pigment Derivative (B′-2)]

913 parts of 98% sulfuric acid (manufactured by NIPPON PHOSPHORIC ACIDCO., JP) and 366 parts of 25% fuming sulfuric acid (manufactured by WakoPure Chemical Industries, Ltd.) were put into a flask equipped with astirrer, a thermometer, and a cooling tube, while being cooled in ice.After the temperature of the flask was increased to 30° C., 70 parts ofphthalimide (manufactured by Wako Pure Chemical Industries, Ltd.) wasadded thereto and the temperature thereof was increased to 40° C.Thereafter, 28 parts of 92% paraformaldehyde (manufactured by MITSUBISHIGAS CHEMICAL COMPANY, INC.) was added thereto and stirred for 30minutes. Next, 81 parts of a zinc phthalocyanine pigment (manufacturedby DIC Corporation) was added thereto and stirred for 30 minutes.Subsequently, the temperature thereof was increased to 70° C. andstirred for 4 hours, and then the temperature was cooled down to roomtemperature. After cooling off, 7500 parts of water having roomtemperature was added thereto and stirred for 1 hour, and then areaction solution was filtered. A filtrate was washed with water untilthe specific conductivity of the filtrate becomes not more than (thespecific conductivity of the original water+50 μS/cm), thereby obtaininga wet cake of a pigment derivative. The obtained wet cake was dried atthe temperature of 90° C. by blowing air for 24 hours to obtain acomparative pigment derivative (B′-2).

The comparative pigment derivative (B′-2) was analyzed according tofield desorption ionization mass spectrometry and it was confirmed thatthe comparative pigment derivative (B′-2) is a compound in which M is azinc atom, a substituent Z is a phthalimide methyl group, and N=1 to 8in General Formula (1). The result of field desorption ionization massspectrometry is shown in Table 7.

TABLE 7 Result of Field Desorption Number of Ionization MassSpectrometry Substituent Z Molecular Ion Peak N m/z Strength Ratio 1 73548.0% 2 894 19.0% 3 1053 14.9% Total of N = 3 4 1212 11.4% to 8: 33.1% 51371 5.0% 6 1530 1.4% 7 1690 0.3% 8 1849 0.1%

Preparation Example 1 [Preparation of Crude Phthalocyanine (C-1)]

270 parts of FASTOGEN Blue RF (α-type copper phthalocyanine pigmentmanufactured by DIC Corporation), 15 parts of FASTOGEN Blue AE-8 (ε-typecopper phthalocyanine pigment manufactured by DIC Corporation), 15 partsof the pigment derivative (B-1), 2400 parts of pulverized sodiumchloride (manufactured by Nihonshokuenseizo Co., Ltd.), and 450 parts ofdiethylene glycol (manufactured by Mitsubishi Chemical Corporation) wereput into a double arm kneader (manufactured by INOUE MFG, INC.), andkneaded at the temperature of 120° C. to 130° C. for 6 hours. Theobtained contents were washed with an excessive amount of water,filtered, and washed with water until the specific conductivity of thefiltrate becomes not more than (the specific conductivity of theoriginal water+50 μS/cm), thereby obtaining a wet cake of the ε-typecopper phthalocyanine pigment. The wet cake was dried at the temperatureof 90° C. by blowing air for 24 hours to obtain crude phthalocyanine(C-1).

Preparation Example 2 [Preparation of Crude Phthalocyanine (C-2)]

270 parts of FASTOGEN Blue RF (α-type copper phthalocyanine pigmentmanufactured by DIC Corporation), 15 parts of FASTOGEN Blue AE-8 (ε-typecopper phthalocyanine pigment manufactured by DIC Corporation), 15 partsof the pigment derivative (B-3), 2400 parts of pulverized sodiumchloride (manufactured by Nihonshokuenseizo Co., Ltd.), and 450 parts ofdiethylene glycol (manufactured by Mitsubishi Chemical Corporation) wereput into a double arm kneader (manufactured by INOUE MFG, INC.), andkneaded at the temperature of 120° C. to 130° C. for 6 hours. Theobtained contents were washed with an excessive amount of water,filtered, and washed with water until the specific conductivity of thefiltrate becomes not more than (the specific conductivity of theoriginal water+50 μS/cm), thereby obtaining a wet cake of the ε-typecopper phthalocyanine pigment. The wet cake was dried at the temperatureof 90° C. by blowing air for 24 hours to obtain crude phthalocyanine(C-2).

Preparation Example 3 [Preparation of Crude Phthalocyanine (C-3)]

270 parts of FASTOGEN Blue RF (α-type copper phthalocyanine pigmentmanufactured by DIC Corporation), 15 parts of FASTOGEN Blue AE-8 (ε-typecopper phthalocyanine pigment manufactured by DIC Corporation), 15 partsof the comparative pigment derivative (B′-1), 2400 parts of pulverizedsodium chloride (manufactured by Nihonshokuenseizo Co., Ltd.), and 450parts of diethylene glycol (manufactured by Mitsubishi ChemicalCorporation) were put into a double arm kneader (manufactured by INOUEMFG, INC.), and kneaded at the temperature of 120° C. to 130° C. for 6hours. The obtained contents were washed with an excessive amount ofwater, filtered, and washed with water until the specific conductivityof the filtrate becomes not more than (the specific conductivity of theoriginal water+50 μS/cm), thereby obtaining a wet cake of the ε-typecopper phthalocyanine pigment. The wet cake was dried at the temperatureof 90° C. by blowing air for 24 hours to obtain crude phthalocyanine(C-3).

Example 1

85 parts of the crude phthalocyanine (C-1), 5 parts of the pigmentderivative (B-1), 10 parts of the polymer (B-5) disclosed inJP-A-2013-228714 as an acryl resin, and 1000 parts of pulverized sodiumchloride (manufactured by Nihonshokuenseizo Co., Ltd.), and 160 parts ofdiethylene glycol (manufactured by Mitsubishi Chemical Corporation) wereput into a double arm kneader (manufactured by INOUE MFG, INC.) andkneaded at the temperature of 80° C. to 90° C. for 12 hours. Theobtained contents were washed with an excessive amount of water,filtered, and washed with water until the specific conductivity of thefiltrate becomes not more than (the specific conductivity of theoriginal water+20 μS/cm), thereby obtaining a wet cake. The obtained wetcake was moved to a beaker, 3000 parts of 2% aqueous hydrochloric acid(manufactured by DAIKIN INDUSTRIES, LTD.) was added thereto, theresultant was stirred and dispersed to obtain a slurry, and the slurrywas stirred at the temperature of 70° C. for 1 hour, and then the slurrywas filtered and washed to obtain a wet cake. The obtained wet cake wasmoved to a beaker, 3000 parts of water having room temperature was addedthereto, and the resultant was stirred and dispersed to obtain a slurry.Subsequently, a sodium hydroxide (manufactured by Wako Pure ChemicalIndustries, Ltd.) aqueous solution of 5 parts of the copperphthalocyanine sulfonic acid derivative (manufactured by DICCorporation) having an average substituent number of 0.8 was added tothe pigment slurry and stirred for 1 hour, and then hydrochloric acid(manufactured by DAIKIN INDUSTRIES, LTD.) was added thereto to returnthe pH of the slurry to 7, and the copper phthalocyanine sulfonic acidderivative was made to be precipitated on the surface of the pigment.The resultant was kept for 1 hour as it is, and then filtered, washedwith warm water, dried, and pulverized, thereby obtaining a blue organicpigment composition (D-1).

20 parts of the blue organic pigment composition (D-1) obtained as theabove was put into a polyethylene bottle, 110 parts of propylene glycolmonomethylether acetate (manufactured by DAICEL Corporation), 14 partsof DISPERBYK LPN21116 (manufactured by BYK Additives & Instruments), and0.3 to 0.4 mmφ SEPR beads (manufactured by Saint-Gobain K.K.) were addedthereto, and the resultant was dispersed by a paint conditioner(manufactured by TOYO SEIKI Co., Ltd.) for 4 hours, thereby obtaining apigment dispersion. 75.00 parts of the pigment dispersion, 5.50 parts ofa polyester acrylate resin (ARONIX M7100, manufactured by TOAGOSEI CO.,LTD.), 5.00 parts of dipentaerythritol hexaacrylate (KAYARAD DPHA,manufactured by Nippon Kayaku Co., Ltd.), 1.00 part of benzophenone(KAYACURE BP-100, manufactured by Nippon Kayaku Co., Ltd.), and 13.5parts of UCAR ester EFP (manufactured by The Dow Chemical Company) werestirred by a dispersing stirrer and filtered by a filter having a poresize of 1.0 μm, thereby obtaining a color resist. The color resist wascoated on a 1 mm glass substrate having a size of 50 mm×50 mm by a spincoater and preliminarily dried at the temperature of 90° C. for 20minutes, thereby forming a coating film. Next, a pattern exposure wasperformed with ultraviolet rays via a photomask, the unexposed area waswashed in a 0.5% sodium carbonate (manufactured by Wako Pure ChemicalIndustries, Ltd.) aqueous solution, and baking was performed at thetemperature of 230° C. for 60 minutes, thereby obtaining a color filter.

With respect to the color filter obtained in Example 1, brightnessdifference ΔY before and after baking at the temperature of 230° C. wasmeasured by MCPD-3000 (manufactured by OTSUKA ELECTRONICS Co., LTD.),and the ΔY was −0.04.

Example 2

The same was performed as Example 1 except that crude phthalocyanine(C-2) was used instead of the crude phthalocyanine (C-1) of Example 1,thereby obtaining a blue organic pigment composition (D-2). A colorfilter was obtained by using this composition, brightness difference ΔYbefore and after baking at the temperature of 230° C. was measured byMCPD-3000 (manufactured by OTSUKA ELECTRONICS Co., LTD.), and the ΔY was−0.03.

Example 3

The same was performed as Example 1 except that crude phthalocyanine(C-3) was used instead of the crude phthalocyanine (C-1) of Example 1and the pigment derivative (B-1) was used instead of the pigmentderivative (B-3), thereby obtaining a blue organic pigment composition(D-3). A color filter was obtained by using this composition, brightnessdifference ΔY before and after baking at the temperature of 230° C. wasmeasured by MCPD-3000 (manufactured by OTSUKA ELECTRONICS Co., LTD.),and the ΔY was −0.06.

Example 4

The same was performed as Example 1 except that crude phthalocyanine(C-3) was used instead of the crude phthalocyanine (C-1) of Example 1and the pigment derivative (B-2) was used instead of the pigmentderivative (B-3), thereby obtaining a blue organic pigment composition(D-4). A color filter was obtained by using this composition, brightnessdifference ΔY before and after baking at the temperature of 230° C. wasmeasured by MCPD-3000 (manufactured by OTSUKA ELECTRONICS Co., LTD.),and the ΔY was −0.07.

Example 5

The same was performed as Example 1 except that crude phthalocyanine(C-3) was used instead of the crude phthalocyanine (C-1) of Example 1,thereby obtaining a blue organic pigment composition (D-5). A colorfilter was obtained by using this composition, brightness difference ΔYbefore and after baking at the temperature of 230° C. was measured byMCPD-3000 (manufactured by OTSUKA ELECTRONICS Co., LTD.), and the ΔY was−0.08.

Example 6

The same was performed as Example 1 except that the comparative pigmentderivative (B′-1) was used instead of the pigment derivative (B-3) ofExample 1, thereby obtaining a blue organic pigment composition (D-6). Acolor filter was obtained by using this composition, brightnessdifference ΔY before and after baking at the temperature of 230° C. wasmeasured by MCPD-3000 (manufactured by OTSUKA ELECTRONICS Co., LTD.),and the ΔY was −0.14.

Example 7

The same was performed as Example 1 except that crude phthalocyanine(C-2) was used instead of the crude phthalocyanine (C-1) of Example 1and the comparative pigment derivative (B′-1) was used instead of thepigment derivative (B-3), thereby obtaining a blue organic pigmentcomposition (D-7). A color filter was obtained by using thiscomposition, brightness difference ΔY before and after baking at thetemperature of 230° C. was measured by MCPD-3000 (manufactured by OTSUKAELECTRONICS Co., LTD.), and the ΔY was −0.13.

Example 8

The same was performed as Example 1 except that crude phthalocyanine(C-2) was used instead of the crude phthalocyanine (C-1) of Example 1and the pigment derivative (B-4) was used instead of the pigmentderivative (B-3), thereby obtaining a blue organic pigment composition(D-8). A color filter was obtained by using this composition, brightnessdifference ΔY before and after baking at the temperature of 230° C. wasmeasured by MCPD-3000 (manufactured by OTSUKA ELECTRONICS Co., LTD.),and the ΔY was −0.08.

Example 9

The same was performed as Example 1 except that crude phthalocyanine(C-2) was used instead of the crude phthalocyanine (C-1) of Example 1and the pigment derivative (B-5) was used instead of the pigmentderivative (B-3), thereby obtaining a blue organic pigment composition(D-9). A color filter was obtained by using this composition, brightnessdifference ΔY before and after baking at the temperature of 230° C. wasmeasured by MCPD-3000 (manufactured by OTSUKA ELECTRONICS Co., LTD.),and the ΔY was −0.05.

Comparative Example 1

The same was performed as Example 1 except that crude phthalocyanine(C-3) was used instead of the crude phthalocyanine (C-1) of Example 1and the comparative pigment derivative (B′-1) was used instead of thepigment derivative (B-3), thereby obtaining a comparative blue organicpigment composition (D′-1). A color filter was obtained by using thiscomposition, brightness difference ΔY before and after baking at thetemperature of 230° C. was measured by MCPD-3000 (manufactured by OTSUKAELECTRONICS Co., LTD.), and the ΔY was −0.18.

Comparative Example 2

The same was performed as Example 1 except that crude phthalocyanine(C-3) was used instead of the crude phthalocyanine (C-1) of Example 1and the comparative pigment derivative (B′-2) was used instead of thepigment derivative (B-3), thereby obtaining a comparative blue organicpigment composition (D′-2). A color filter was obtained by using thiscomposition, brightness difference ΔY before and after baking at thetemperature of 230° C. was measured by MCPD-3000 (manufactured by OTSUKAELECTRONICS Co., LTD.), and the ΔY was −0.20.

A summary of the above-mentioned Synthesis Examples 1 to 7 is shown inTable 8 and evaluation results of Examples 1 to 9 and ComparativeExamples 1 and 2 are shown in Table 9.

TABLE 8 Sum of Central Strength ratio Pigment Derivative (B) Metal M ofN = 3 to 8 Synthesis Pigment Derivative (B-1) Copper 26.50% Example 1Synthesis Pigment Derivative (B-2) Copper 21.20% Example 2 SynthesisPigment Derivative (B-3) Copper 17.60% Example 3 Synthesis PigmentDerivative (B-4) Zinc 25.20% Example 4 Synthesis Pigment Derivative(B-5) Zinc 16.40% Example 5 Synthesis Comparative Pigment Copper 31.00%Example 6 Derivative (B′-1) Synthesis Comparative Pigment Zinc 33.10%Example 7 Derivative (B′-2)

TABLE 9 Pigment Brightness Crude Pigment Derivative Derivative BlueOrganic Difference ΔY Phthalocyanine (B) in Crude (B) used in Pigmentbefore and (C) Phthalocyanine (C) Examples Composition (D) after bakingExample 1 Crude Pigment Pigment Blue Organic −0.04 PhthalocyanineDerivative Derivative Pigment (C-1) (B-1) (B-3) Composition (D-1)Example 2 Crude Pigment Pigment Blue Organic −0.03 PhthalocyanineDerivative Derivative Pigment (C-2) (B-3) (B-3) Composition (D-2)Example 3 Crude Comparative Pigment Blue Organic −0.06 PhthalocyaninePigment Derivative Pigment (C-3) Derivative (B-1) Composition (B′-1)(D-3) Example 4 Crude Comparative Pigment Blue Organic −0.07Phthalocyanine Pigment Derivative Pigment (C-3) Derivative (B-2)Composition (B′-1) (D-4) Example 5 Crude Comparative Pigment BlueOrganic −0.08 Phthalocyanine Pigment Derivative Pigment (C-3) Derivative(B-3) Composition (B′-1) (D-5) Example 6 Crude Pigment Comparative BlueOrganic −0.13 Phthalocyanine Derivative Pigment Pigment (C-1) (B-1)Derivative Composition (B′-1) (D-6) Example 7 Crude Pigment ComparativeBlue Organic −0.12 Phthalocyanine Derivative Pigment Pigment (C-2) (B-3)Derivative Composition (B′-1) (D-7) Comparative Crude ComparativeComparative Comparative −0.18 Example 1 Phthalocyanine Pigment PigmentBlue Organic (C-3) Derivative Derivative Pigment (B′-1) (B′-1)Composition (D′-1) Example 8 Crude Pigment Pigment Blue Organic −0.08Phthalocyanine Derivative Derivative Pigment (C-2) (B-3) (B-4)Composition (D-8) Example 9 Crude Pigment Pigment Blue Organic −0.05Phthalocyanine Derivative Derivative Pigment (C-2) (B-3) (B-5)Composition (D-9) Comparative Crude Comparative Comparative Comparative−0.2 Example 2 Phthalocyanine Pigment Pigment Blue Organic (C-3)Derivative Derivative Pigment (B′-1) (B′-2) Composition (D′-2)

As understood from comparison between Examples 1 to 7 and ComparativeExample 1 shown in the above Table 9 and comparison between Examples 8and 9 and Comparative Example 2, if the pigment derivative (B), in whicha sum of the strength ratio of the pigment derivative having an N of 3to 8 in field desorption ionization mass spectrometry is 30% or less ofa sum of the strength ratio of pigment derivatives having an N of 1 to8, is used, it is apparent to obtain an organic pigment compositionwhose brightness difference ΔY before and after baking is remarkablysmall and heat resistance is extremely high. In addition, in the pigmentderivative used when preparing an ε-type copper phthalocyanine from anα-type copper phthalocyanine pigment and the pigment derivative usedwhen synthesizing a blue organic pigment composition from the ε-typecopper phthalocyanine, the above-mentioned both pigment derivatives maybe the pigment derivative (B) in which a sum of strength ratio of thepigment derivative having an N of 3 to 8 is 30% or less, or even if onlyone of the above-mentioned pigments is the pigment derivative (B), anorganic pigment composition having remarkably high heat resistance isobtained.

The invention claimed is:
 1. An organic pigment composition for colorfilters, comprising: a phthalocyanine pigment (A); and a pigmentderivative (B) represented by General Formula (1):

wherein in General Formula (1), M represents a metal which may have asubstituent or 2H, Z represents a phthalimide alkyl group which may havea substituent, n1, n2, n3, and n4 represent the number of thesubstituent Z and each independently is an integer of 0 to 4, providedthat when N=n1+n2+n3+n4, a relation of 1≤N≤8 is satisfied, a sum of thestrength ratio of pigment derivatives having an N of 3 to 8 in fielddesorption ionization mass spectrometry is 30% or less of a sum of thestrength ratio of pigment derivatives having an N of 1 to 8, a strengthratio of pigment derivative of N=2 in field desorption ionization massspectrometry is 20% or more of a sum of the strength ratio of pigmentderivatives having an N of 1 to 8, and a strength ratio of pigmentderivative of N=5 is 0.7% or more and less than 5.1% of a sum of thestrength ratio of pigment derivatives having an N of 1 to
 8. 2. Theorganic pigment composition for color filters according to claim 1,wherein in General Formula (1), a sum of the strength ratio of pigmentderivatives having an N of 4 to 8 in field desorption ionization massspectrometry is 15% or less of a sum of the strength ratio of pigmentderivatives having an N of 1 to
 8. 3. A method for producing the organicpigment composition for color filters according to claim 2 comprising: astep of performing solvent salt milling of a mixture which includescrude phthalocyanine or the phthalocyanine pigment (A), the pigmentderivative (B) represented by General Formula (1), a water-solubleinorganic salt, and a water-soluble organic solvent.
 4. The method forproducing the organic pigment composition for color filters according toclaim 3, wherein the mixture, which includes crude phthalocyanine or thephthalocyanine pigment (A), the pigment derivative (B) represented byGeneral Formula (1), a water-soluble inorganic salt, and a water-solubleorganic solvent, further includes an acryl resin.
 5. A color filtercomprising: the organic pigment composition for color filters obtainedby the method for producing an organic pigment composition for colorfilters according to claim
 3. 6. A color filter comprising: the organicpigment composition for color filters according to claim
 2. 7. Theorganic pigment composition for color filters according to claim 1,wherein M in General Formula (1) represents a monovalent to tetravalentmetal which may have a substituent.
 8. A method for producing theorganic pigment composition for color filters according to claim 7comprising: a step of performing solvent salt milling of a mixture whichincludes crude phthalocyanine or the phthalocyanine pigment (A), thepigment derivative (B) represented by General Formula (1), awater-soluble inorganic salt, and a water-soluble organic solvent. 9.The method for producing the organic pigment composition for colorfilters according to claim 8, wherein the mixture, which includes crudephthalocyanine or the phthalocyanine pigment (A), the pigment derivative(B) represented by General Formula (1), a water-soluble inorganic salt,and a water-soluble organic solvent, further includes an acryl resin.10. A color filter comprising: the organic pigment composition for colorfilters obtained by the method for producing an organic pigmentcomposition for color filters according to claim
 8. 11. A color filtercomprising: the organic pigment composition for color filters accordingto claim
 7. 12. The organic pigment composition for color filtersaccording to claim 1, wherein 0.1 parts to 50.0 parts of the pigmentderivative (B) represented by General Formula (1) are included per 100parts of the phthalocyanine pigment (A) by mass.
 13. A method forproducing the organic pigment composition for color filters according toclaim 12 comprising: a step of performing solvent salt milling of amixture which includes crude phthalocyanine or the phthalocyaninepigment (A), the pigment derivative (B) represented by General Formula(1), a water-soluble inorganic salt, and a water-soluble organicsolvent.
 14. The method for producing the organic pigment compositionfor color filters according to claim 13, wherein the mixture, whichincludes crude phthalocyanine or the phthalocyanine pigment (A), thepigment derivative (B) represented by General Formula (1), awater-soluble inorganic salt, and a water-soluble organic solvent,further includes an acryl resin.
 15. A color filter comprising: theorganic pigment composition for color filters according to claim
 12. 16.A method for producing the organic pigment composition for color filtersaccording to claim 1 comprising: a step of performing solvent saltmilling of a mixture which includes crude phthalocyanine or thephthalocyanine pigment (A), the pigment derivative (B) represented byGeneral Formula (1), a water-soluble inorganic salt, and a water-solubleorganic solvent.
 17. The method for producing the organic pigmentcomposition for color filters according to claim 16, wherein themixture, which includes crude phthalocyanine or the phthalocyaninepigment (A), the pigment derivative (B) represented by General Formula(1), a water-soluble inorganic salt, and a water-soluble organicsolvent, further includes an acryl resin.
 18. A color filter comprising:the organic pigment composition for color filters obtained by the methodfor producing an organic pigment composition for color filters accordingto claim
 17. 19. A color filter comprising: the organic pigmentcomposition for color filters according to claim
 1. 20. A color filtercomprising: the organic pigment composition for color filters obtainedby the method for producing an organic pigment composition for colorfilters according to claim 16.